Rooms, particularly bathrooms, with poor ventilation can be regularly subjected to humid conditions. Under such conditions, moist air can have difficulty exiting the room, resulting in condensation or dewing on the room's surfaces. Moisture, in general, can lead to mold growth. Mold has been known to cause serious illness and extensive property damage.
Typically, rooms subject to high humidity contain ventilation systems that use an exhaust fan to expel the humid air from the room to the atmosphere, but these systems have known deficiencies. First, most ventilation systems are limited by their dependence on human operators to manually actuate a power switch. However, people often forget to activate the switch, especially before it is needed. Therefore, high moisture conditions exist by the time the system is activated, if it ever is.
A second type of ventilation system operates by activating the exhaust fan when the room's lights are turned on. These ventilation systems are uneconomical because they always activate the fan, even during non-humid conditions. Besides increased power usage, these systems needlessly expel conditioned air (heated or cooled) from the room. Other problems include users shutting off the lights before the excess moisture has been fully removed from the room, or they may never turn on the room's lights to begin with.
Other ventilation systems employ timers to activate and deactivate the ventilation system. These systems are also wasteful if they continue to run after the humidity has already been expelled. On the other hand, timed systems may not run long enough to fully dehumidify the room. Basically, these ventilation systems are ineffective and wasteful because they are not automated. They also do not ensure that moisture will be adequately removed from a room.
Improvements to known ventilation systems have been made in an effort to increase system automation and effectiveness. Humidity sensors are now used to detect high humidity conditions so that a ventilation system activates once a room's humidity exceeds a preset value. These settings are often predefined and may not apply to the environmental conditions for various geographical areas. Moreover, the humidity inside a building varies throughout the course of a day with temperature fluctuations, as well as during different seasons of the year. As a result, it is possible the device will perform poorly because the operating parameters, such as geographical and seasonal changes, were not accounted for.
Another effort to automate ventilation systems for humid environments includes a device using one sensor to monitor a room's humidity and circuitry to calculate average humidity over a given period of time in order to form a reference value. If the measured humidity exceeds this reference value by a predetermined amount, a ventilation controller activates an exhaust fan. A drawback to this method is that environmental humidity can fluctuate as the temperature changes each day, causing the ambient humidity to exceed the reference value. As a result, the fan may fail to operate when it is needed or may operate needlessly.
It can be seen that a need exists for a ventilation system that is fully automated, economical, and effective. It would be an improvement to have an exhaust fan automatically activated when the humidity level in a room increases above a control point but wherein a user sets the control point. In this manner, a user could account for the particular conditions of their locale. Another improvement would include a ventilation system wherein a ventilation controller activates an exhaust fan when rapidly increasing humidity is detected. In yet another improvement, a ventilation system would include a ventilation controller that activates an exhaust fan when the humidity in a room exceeds the humidity in nearby rooms. Preferably, these improvements could be used in combination with each other could include the use of wireless technology. For example, humidity sensors used to monitor the humidity in a room could communicate with the ventilation controller without a wired connection. In any event, an improved ventilation controller would only operate an exhaust fan as needed, and it would also be constructed to be mounted inside, or in place of, a standard electrical junction box such as one containing light switches. The ventilation system in accordance with the present invention provides such a ventilation controller, and it overcomes the deficiencies that have prevented the development of a satisfactory ventilation controller.